U.S. Pat. No. 2,245,875 discloses a toy formed by a plurality of foldable hinge unit connected in series. With reference to FIGS. 19-20, each unit comprises two plates 40, 41 connected by three ribbons. Two ribbons 42 are used to connect the left ends of the two plates 40, 41. The remaining ribbon 47 is located between the two ribbons 42 and used to connect the right ends of the two plates 40, 41. The first plate 40 can be rotated 180 degrees clockwise with respect to the left end of the second plate 41 so that the first plate 40 covers the second plate 41. Then the first plate 40 can be further rotated 180 degrees clockwise with respect to the right end of the second plate 41. After that, the first plate 40 will be on the right side of the second plate 41.
In order to avoid obstructing the rotational movements, the two plates in U.S. Pat. No. 2,245,875 are connected by ribbons having a negligible thickness. As a result, the disclosed structure may not be able to meet the requirements of industrial applications.